Cyclic AMP (cAMP) is an important second messenger that activates several target molecules, including cAMP dependent protein kinases, cyclic nucleotide gated ion channels, and cAMP receptors. Such activation results in the modulation of diverse phenomena such as metabolism, olfaction, heart rate, differentiation, learning and memory. The activities of many adenylyl cyclases are controlled dynamically by a variety of hormones, neurotransmitters, and other regulatory molecules. Each isoform has its distinct tissue distribution and unique regulatory properties, providing ways for different cells to respond diversely to similar stimuli. There is a need for experimental models which will allow us to investigate and possibly predict the potential side-effects of administration of biological agents which may modulate the adenylyl cyclase system. We have initiated studies aimed at investigating whether exposure of slide-mounted rat brain sections to biologics such as neurotrophic factors, growth factors, and cytokines results in modulations in the regulation of the adenylyl cyclase system. This research is aimed at probing the modes of regulation of adenylyl cyclase, an enzyme which plays a pivotal role in signal transduction. Several of the neurotrophic and growth factors, as well as cytokines, that are regulated by the division activate cells through adenylyl cyclase. Characterization of this enzyme and its role in signal transduction enables us to better understand how these biologics activate cells and helps us prevent potential adverse reactions when they are used in conjunction with other drugs that modulate adenylyl cyclase activity.